#!/usr/bin/env ruby

# frozen_string_literal: true

require 'digest'
require 'fileutils'

if ENV['NO_COLOR']
  SHELL_RED    = ''
  SHELL_GREEN  = ''
  SHELL_YELLOW = ''
  SHELL_CLEAR  = ''
else
  SHELL_RED    = "\e[1;31m"
  SHELL_GREEN  = "\e[1;32m"
  SHELL_YELLOW = "\e[1;33m"
  SHELL_CLEAR  = "\e[0m"
end

LEFTHOOK_GLOBAL_CONFIG_PATH = File.expand_path("../lefthook.yml", __dir__)
HOOK_PATH = `git rev-parse --path-format=absolute --git-path hooks/pre-push`.split.last
HOOK_DATA = <<~HOOK
  #!/usr/bin/env bash

  set -e

  url="$2"

  if [[ "$url" != *"gitlab-org/security/"* ]]
  then
    echo "Pushing to remotes other than gitlab.com/gitlab-org/security has been disabled!"
    echo "Run scripts/security-harness to disable this check."
    echo

    exit 1
  fi
HOOK

def hook_exist?
  File.exist?(HOOK_PATH)
end

def lefthook_hook_in_place?
  hook_exist? && File.foreach(HOOK_PATH).grep(/lefthook/i).any?
end

def lefthook_available?
  system('bundle exec lefthook run prepare-commit-msg &>/dev/null') # rubocop:disable GitlabSecurity/SystemCommandInjection
end

def uninstall_lefthook
  return unless lefthook_available?

  system('bundle exec lefthook uninstall') # rubocop:disable GitlabSecurity/SystemCommandInjection
  # `bundle exec lefthook uninstall` removes the `lefthook.yml` file so we checkout it again
  system("git checkout -- #{LEFTHOOK_GLOBAL_CONFIG_PATH}") # rubocop:disable GitlabSecurity/SystemCommandInjection
  puts "#{SHELL_YELLOW}Lefthook was uninstalled to let the security harness work properly.#{SHELL_CLEAR}"
end

def install_lefthook
  return unless lefthook_available?

  system('bundle exec lefthook install') # rubocop:disable GitlabSecurity/SystemCommandInjection
  puts "#{SHELL_GREEN}Lefthook was re-installed.#{SHELL_CLEAR}"
end

def write_hook
  FileUtils.mkdir_p(File.dirname(HOOK_PATH))
  File.open(HOOK_PATH, 'w') do |file|
    file.write(HOOK_DATA)
  end
  File.chmod(0755, HOOK_PATH)
  puts "#{SHELL_GREEN}Security harness installed -- you will only be able to push to gitlab.com/gitlab-org/security!#{SHELL_CLEAR}"
end

def delete_hook
  FileUtils.rm(HOOK_PATH)
  system("git checkout master")
  puts "#{SHELL_YELLOW}Security harness removed -- you can now push to all remotes.#{SHELL_CLEAR}"
end

def hook_file_sum
  Digest::SHA256.file(HOOK_PATH).hexdigest
end

def hook_data_sum
  Digest::SHA256.hexdigest(HOOK_DATA)
end

# If we were to change the script and then check for a pre-existing hook before
# writing, the check would fail even if the user had an unmodified version of
# the old hook. Checking previous version hashes allows us to safely overwrite a
# script that differs from the current version, as long as it's an old one and
# not custom.
def upgrade_available?
  # SHA256 hashes of previous iterations of the script contained in `HOOK_DATA`
  %w[
    010bf0363a911ebab2bd5728d80795ed02388da51815f0b2530d08ae8ac574f0
    d9866fc672f373d631eed9cd8dc9c920fa3d36ff26d956fb96a4082a0931b371
  ].include?(hook_file_sum)
end

def current_version?
  hook_data_sum == hook_file_sum
end

# Uninstall Lefthook if it's in place
uninstall_lefthook if lefthook_hook_in_place?

if hook_exist?
  # Deal with a pre-existing hook
  if upgrade_available?
    # Upgrading from a previous version, update in-place
    write_hook
  elsif current_version?
    # Delete the hook if we're already using the current version
    delete_hook

    # Re-install Lefthook pre-push hook
    install_lefthook
  else
    # Pre-existing hook we didn't create; do nothing
    puts "#{SHELL_RED}#{HOOK_PATH} exists and is different from our hook!"
    puts "Remove it and re-run this script to continue.#{SHELL_CLEAR}"

    exit 1
  end
else
  write_hook
end
